It will be clearly understood that, although a number of prior art publications are referred to herein to describe background information, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art, in Australia or in any other country. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents.
Some references are made in the detailed description to documents that describe certain features of the present invention. Such references, including patents or patent applications, are hereby incorporated by reference.
Asthma is a chronic disease characterized by intermittent, reversible, widespread constriction of the airways of the lungs in response to any of a variety of stimuli which do not affect the normal lung. There is chronic inflammation and paradoxical narrowing of the bronchi, and recurrent acute episodes of limited airflow, mucus production and cough. The symptoms, which are provoked by allergens such as pollens, mould spores, pet or other animal danders and house dust mites, or by environmental triggers such as tobacco smoke or other air pollutants, include wheezing, shortness of breath, difficulty in breathing, especially on exhalation, and tightness of the chest. Other triggers include infections such as colds and other upper respiratory infections, viruses or sinus infections, irritants such as strong odours from perfumes or cleaning solutions, exercise or exertion, changes in temperature or humidity, stress and strong emotion. Asthma which is provoked by allergens is generally known as allergic asthma or atopic asthma.
Type 1 (immediate) immune responses may play an important role in the development of asthma in children and many adults; however, when the onset of disease occurs in adulthood, allergic factors may be difficult to identify.
Thus asthma is broadly divided into two types: extrinsic asthma, which is also known as allergic or atopic asthma, and intrinsic or non-atopic asthma. These two subclasses of asthma are referred to herein as allergic and non-allergic asthma respectively. The immunopathology of these two forms of asthma has been reviewed by Humbert M. et al. 1999. Allergic asthma is characterised by infiltration of eosinophils and T helper 2 (Th2)-type cells into the bronchial mucosa, the presence of specific immunoglobulin E (IgE) antibodies in the circulation, positive skin test reactions to common airborne allergens, and airway hyper-responsiveness. Synthesis of IgE by B cells is believed to be stimulated by interleukin-4 (IL-4), and mobilisation of eosinophils is believed to be stimulated by interleukin-5 (IL-5). In contrast to this, patients suffering from non-allergic asthma have negative skin tests, and have no clinical or family history of allergy, and they have no specific IgE antibodies directed against common allergens. Moreover, these patients are usually older than those with allergic asthma, and their symptoms first present in later life; they often manifest a more severe clinical course.
Studies on bronchial biopsy samples showed that both forms of asthma were characterised by infiltration of eosinophils and Th2 cells secreting IL-4, IL-5 or both of these cytokines; the presence of CC chemokines and FcεRI+ cells; and cells which express mRNA for the ε germ-line transcript (Iε) and the ε heavy chain of IgE (Cε). The only apparent difference was a marked elevation in CD68+ macrophages expressing the GM-CSF receptor α subunit in patients with non-allergic asthma, compared with those suffering from allergic asthma (Humbert M. et al. 1999). Since both T cells and B cells are implicated in asthmatic responses, particularly in the production of IgE, modulation of both T and B cell responses would be expected to be useful in the treatment of extrinsic and intrinsic asthma.
Asthma affects 12-15 million Americans, including approximately 10%-12% of children under the age of 18. Between about 10% and 33% of all patients with asthma have the non-allergic form. People who have a family history of asthma have an increased risk of developing the disease. Asthma is also more common in people who have allergies or who are exposed to tobacco smoke. Asthma often develops in childhood or the teenage years, and is the most common chronic childhood disease. Although it is more common in individuals under 40 years old, asthma can develop at any age.
Treatment of asthma focuses on the use of medications which control inflammation and prevent chronic symptoms (long-term control medications) and medications which treat asthma attacks when they occur (quick relief medications), and avoiding asthma triggers. There are two general types of asthma medications:
(a) Anti-inflammatory drugs, which prevent asthma attacks on an ongoing basis. Steroids, also called “corticosteroids,” are an important type of anti-inflammatory medication for people suffering from asthma. These drugs reduce swelling and mucus production in the airways. As a result, the airways are less sensitive and less likely to react to triggers.(b) Bronchodilators, which relieve the symptoms of asthma by relaxing the muscle bands that tighten around the airways. This action rapidly opens the airways, letting more air to enter and leave the lungs. As a result, breathing improves. Bronchodilators also help to clear mucus from the lungs. As the airways open, the mucus moves more freely and can be coughed out more easily.
In addition to these conventional medications, a recombinant humanized monoclonal antibody against IgE (Xolair; Genentech, Inc), was approved in June 2003. This antibody blocks binding of IgE to mast cells and basophils, thus inhibiting the allergic reaction which causes constriction of the airways.
Preventing the inflammation is the key to preventing asthma attacks, hospitalizations and death from asthma. Long-term control medications are taken daily over an extended period of time to achieve and maintain control of persistent asthma, ie asthma which causes symptoms more than twice a week and frequent attacks which affect activity.
The most effective long-term control medications are anti-inflammatory drugs, but there are others which are often used along with anti-inflammatory drugs to enhance their effect. These medications include:
1. Corticosteroids: the inhaled form is the anti-inflammatory drug of choice for persistent asthma;
2. Mast cell stabilizers: anti-inflammatory drugs;
3. Long acting β-agonists: bronchodilators often used along with an anti-inflammatory drug;
4. Theophylline: a bronchodilator used along with anti-inflammatory to prevent nighttime symptoms; and
5. Leukotriene modifiers: an alternative to steroids and mast cell stabilizers.
Despite the availability of all these medications, asthma is frequently very difficult to control, and each year acute asthma attacks (status asthmaticus) result in frequent hospital admissions, especially among children, and in a significant number of deaths.
Asthma is regarded as being a quite different condition from allergic alveolitis, which is also known as extrinsic allergic alveolitis, allergic interstitial pneumonitis, extrinsic allergic pneumonia or hypersensitivity pneumonitis. Extrinsic allergic alveolitis is a relatively rare lung disorder resulting from repeated inhalation of organic dust, usually in a specific occupational setting. In the acute form, respiratory symptoms and fever begin several hours after exposure to the dust. The chronic form is characterized by gradual changes in the lung tissue associated with several years of exposure to the irritant. It has been variously named bagassosis, bathtub refinisher's lung, bird or pigeon breeder's disease, cheese worker's lung, enzyme detergent sensitivity, epoxy resin lung, farmer's lung, laboratory technician's lung, maltworker's lung, maple bark-stripper's disease, mushroom picker's disease, mushroom worker's lung, snuff-taker's lung, plastic worker's lung, poultry breeder's disease, sequoiosis, suberosis, ventilation pneumonitis, and wheat weevil disease, depending on the initiating agent.
Chronic obstructive pulmonary disease (COPD), also known as chronic obstructive lung disease (COLD) or chronic airflow obstruction (CAO), is a group of diseases principally consisting of emphysema, obliterative bronchiolitis and chronic bronchitis. COPD is the fourth leading cause of death in the United States, and is a leading cause of disability. Approximately 15 million Americans are affected by COPD, and there is an increasing incidence in women. COPD is a chronic progressive disease process which most commonly results from smoking, but may also be provoked by prolonged exposure to other lung irritants such as industrial dust or chemical fumes. Genetic factors, low birth weight or repeated lung infections may increase susceptibility to COPD. COPD develops over a long period, sometimes as much as 10 to 30 years, and is most commonly diagnosed at the age of 60 or greater. Consequently COPD is generally regarded as a disease of older adults. COPD is characterised by difficulty in breathing, wheezing and a chronic cough. Treatment includes absolute avoidance of smoking, with the use of bronchodilators and oxygen for those with advanced disease, and emphysema patients may undergo surgery to reduce lung volume. COPD patients are subject to periodic exacerbations of the condition which result in a rapid increase in shortness of breath, which may be life-threatening.
Chronic bronchitis (CB) is inflammation of one or more bronchi, usually secondary to infection, and is characterized by excessive production of mucus in the bronchi, accompanied by a recurrent cough which persists for at least three months of the year during at least two successive years. CB is the major non-asthmatic disease of the lung. Many different factors initiate CB, including cigarette smoking, environmental pollution, chronic infections and various genetic abnormalities. Of these factors, cigarette smoking is the most prevalent. Pathological changes in the lung include:
(1) hypertrophy and hyperplasia of mucus-secreting glands in the bronchi,
(2) increase in goblet cells,
(3) disappearance or damage of cilia, and
(4) chronic inflammatory changes and narrowing of small airways.
A bacterial or viral infection is often present. Excess amounts of mucus are found in the airways, and sometimes may occlude small bronchioles. Eventually there may be scarring of the bronchial wall. Coughing is stimulated by retained mucus, which cannot be adequately removed due to decreased cilia and lessened mucociliary clearance (Svartengren et al. 1996). It is important that bronchitis patients clear retained mucus by coughing; however, often coughing is ineffective in adequately removing these secretions because the bronchitis patient cannot inspire deeply enough to cause air to flow distal to retained secretions.
Emphysema is a lung condition which results from damage to the alveolar sacs in the lungs, usually caused by long-term smoking. This damage leads to a pathological accumulation of air in the tissues.
The reduction of chronic inflammation by the inhibition of T-cell and B-cell function in emphysema, obliterative bronchiolitis and chronic bronchitis, and consequent reduction in the narrowing of small airways in patients suffering from these conditions, would greatly reduce the burden on the health system caused by these common debilitating diseases.
The T cell receptor (TCR) is composed of at least seven transmembrane proteins. The disulphide-linked (αβ-Ti) heterodimer forms the clonotypic antigen recognition unit, while the invariant chains of CD3, consisting of γ, δ, ε, ζ and η chains, are responsible for coupling the ligand binding to signalling pathways which result in T-cell activation and the elaboration of the cellular immune responses. Despite the diversity of the genes encoding the TCR polypeptide chains, two structural features are common to all known TCR subunits. Firstly, they are transmembrane proteins with a single transmembrane spanning domain, which is presumably α-helical. Secondly, all the TCR chains share the unusual feature of possessing a charged amino acid within the predicted transmembrane domain. The invariant chains have a single negative charge, conserved between the mouse and human, and the variant chains possess one (TCRβ) or two (TCRα) positive charges.
International patent applications No. PCT/AU96/00018 and No. PCT/AU97/00367 by Northern Sydney Area Health Services disclose peptides which are able to inhibit the function of the mammalian T-cell receptor for antigen (TCR). The entire contents of these two documents are incorporated herein by this reference. These peptides were designed on the basis of the discovery that the stable interaction between the TCR-α chain and the CD3-δ and CD3-ε subunits was localised to 8 amino acids within the transmembrane domain of TCR-α, and that charged amino acids were critical for this interaction, as disclosed in PCT/AU96/00018. Additional peptides were based on sequences from peptides corresponding to alternative chain assembly regions in the CD3-δ, -ε and -γ chains, the TCR-αβ interchain disulphide bond interaction region, and regions downstream of the core peptide (GFRILLLKV (SEQ ID NO: 26) (human) or GLRILLLKV (SEQ ID NO: 27) (murine)). These are disclosed in PCT/AU97/00367. These peptides were shown to be able to penetrate into cells, and to decrease the symptoms of T cell-mediated inflammation in vivo in the adjuvant-induced arthritis model in rats. The results were also reported in the literature (Manolios et al. 1997). The entire contents of this document are incorporated herein by this reference.
It was proposed that the peptides would be useful in the treatment of a variety of disorders in which T cells are involved or in which T cells are recruited to the site of the pathology, including rheumatoid arthritis. One of these peptides, corresponding to a 9-amino acid region in the transmembrane domain of the TCR-α chain, can suppress T cell function both in vitro and in vivo, and inhibits production of interleukin-2 following antigen-induced stimulation Rang et al. 2002). It has also been demonstrated that a 9-amino acid peptide, Gly-Leu-Arg-Ile-Leu-Leu-Leu-Lys-Val (SEQ ID NO: 1), designated “core peptide”, inhibited development of contact sensitivity when applied topically following application of a contact allergen in sensitised animals (Enk and Knop 2000; Gollner et al 2000; Manolios et al. 2002). Enk and Knop and Gollner et al. also showed that subcutaneous injection of naked DNA encoding the peptide sequence prior to application of the contact allergen prevented development of contact sensitivity. The peptide showed therapeutic activity in human patients with psoriasis, atopic eczema, lichen planus, or contact dermatitis, and they concluded that the peptide, or DNA encoding it, would be useful as an alternative to corticosteroids in treatment of human T cell-mediated dermatoses.